U.S. patent number 11,300,119 [Application Number 17/183,067] was granted by the patent office on 2022-04-12 for system for driving a pulsatile fluid pump.
This patent grant is currently assigned to VentriFlo, Inc.. The grantee listed for this patent is VentriFlo, Inc.. Invention is credited to Brian Bailey, Conrad Bzura, Judy Labonte, Matthew J. Murphy, Jeffrey P. Naber, David Olney, Patrick Shields, Eric Smith, Douglas E. Vincent, Kathleen Vincent.
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United States Patent |
11,300,119 |
Vincent , et al. |
April 12, 2022 |
System for driving a pulsatile fluid pump
Abstract
A pulsatile fluid pump system for driving a fluid pump assembly
includes a reciprocating linear motor having a magnet and a coil,
the magnet moving in relation to the coil, the coil having an
electrical input. The pulsatile fluid pump system further includes
a controller system having an electrical output coupled to the
electrical input of the coil, and the controller system is
configured to execute a waveform program defining an electrical
waveform at the electrical output. The waveform program is
configured to control operation of the linear motor by modification
of a feature, selected from the group consisting of amplitude,
frequency, shape, and combinations thereof, of the electrical
waveform at the electrical output. The waveform program is further
configured to accept a set of user-specifiable parameters defining
the performance of the linear motor and to modify the electrical
waveform in response to such parameters.
Inventors: |
Vincent; Douglas E. (Pelham,
NH), Bailey; Brian (Chelmsford, MA), Bzura; Conrad
(Melrose, MA), Olney; David (Chester, NH), Smith;
Eric (Newburyport, MA), Naber; Jeffrey P. (Mont Vernon,
NH), Labonte; Judy (Hudson, NH), Vincent; Kathleen
(Pelham, NH), Murphy; Matthew J. (Marshfield, MA),
Shields; Patrick (Westford, MA) |
Applicant: |
Name |
City |
State |
Country |
Type |
VentriFlo, Inc. |
Pelham |
NH |
US |
|
|
Assignee: |
VentriFlo, Inc. (Pelham,
NH)
|
Family
ID: |
81123795 |
Appl.
No.: |
17/183,067 |
Filed: |
February 23, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B
49/065 (20130101); A61M 60/178 (20210101); F04B
43/02 (20130101); A61M 60/457 (20210101); A61M
60/546 (20210101); A61M 60/894 (20210101); A61M
60/585 (20210101); F04B 17/03 (20130101); F04B
43/09 (20130101); A61M 60/247 (20210101); A61M
2205/505 (20130101); A61M 2205/3334 (20130101) |
Current International
Class: |
F04B
43/02 (20060101); A61M 60/457 (20210101); A61M
60/585 (20210101); F04B 49/06 (20060101); A61M
60/247 (20210101); A61M 60/546 (20210101); A61M
60/894 (20210101); A61M 60/178 (20210101); F04B
43/09 (20060101); F04B 17/03 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
International Searching Authority--International Search Report,
pertaining to International Application No. PCT/US2021/019262,
dated Nov. 10, 2021, together with the Written Opinion of the
International Searching Authority, 14 pages. cited by
applicant.
|
Primary Examiner: Hamo; Patrick
Attorney, Agent or Firm: Sunstein LLP
Claims
What is claimed is:
1. A pulsatile fluid pump system for driving a fluid pump assembly,
the pulsatile fluid pump system comprising: a reciprocating linear
motor having a magnet and a coil, the magnet moving in relation to
the coil, the coil having an electrical input; a controller system
having an electrical output coupled to the electrical input of the
coil and a storage system in which is stored an archetype
electrical waveform, the controller system being configured to
execute a waveform program defining an electrical waveform at the
electrical output; wherein the waveform program is configured to
accept user-provided values of a set of user-specifiable parameters
defining performance of the linear motor and further configured to
read the archetype electrical waveform from the storage system and
to generate the electrical waveform at the electrical output by
modifying the archetype electrical waveform with respect to a
feature, selected from the group consisting of amplitude,
frequency, shape, and combinations thereof, in response to the
user-provided values for such parameters.
2. A pulsatile fluid pump system according to claim 1, further
comprising a graphic display, coupled to the controller system, the
controller system executing a graphics program configured to cause
the graphic display to show the user-provided values of the set of
user-specifiable parameters defining the performance of the linear
motor.
3. A pulsatile fluid pump system according to claim 2, further
comprising a flow sensor mechanically coupled to a fluid path
including the integrated pump assembly, the flow sensor having an
electrical output coupled to the controller system, wherein the
controller system is executing a graphics program configured to
cause the graphic display to show a set of items, including values
of a set of physical flow characteristics.
4. A pulsatile fluid pump system according to claim 3, wherein the
set of items shown includes an instantaneous flow rate waveform in
near real-time.
5. A pulsatile fluid pump system according to claim 3, wherein the
set of items shown includes an instantaneous stroke volume waveform
in near real-time.
6. A pulsatile fluid pump system according to claim 1, wherein the
waveform program is configured to generate the electrical waveform
at the electrical output by repeatedly performing a multi-piece
polynomial spline algorithm in a manner responsive to the
user-provided values of the set of user-specifiable parameters
defining the performance of the linear motor.
7. A pulsatile fluid pump system according to claim 1, further
comprising a set of sensors, electrically coupled to the controller
system and configured to produce a set of sensor outputs
corresponding to pumping performance, wherein the waveform program
is configured to generate the electrical waveform at the electrical
output in a manner responsive to the set of sensor outputs and the
user-provided values of the set of user-specifiable parameters.
8. A pulsatile fluid pump system according to claim 1, wherein the
user of the pulsatile fluid pump system may choose from a set of
waveform programs.
9. A pulsatile fluid pump system according to claim 2, wherein the
graphic display is touch sensitive.
Description
RELATED APPLICATIONS
The present application is one of four applications being filed on
the same day and bearing U.S. Ser. Nos. 17/182,915, 17/182,893,
17/183,067, and 17/183,080. Each of these related applications,
other than the present application, is hereby incorporated herein
by reference in its entirety.
TECHNICAL FIELD
The present invention relates to pulsatile fluid pumps, and more
particularly to pulsatile fluid pumps suitable for pumping
blood.
BACKGROUND ART
A pulsatile fluid pump is taught in U.S. Pat. No. 7,850,593 ("our
prior patent") for an invention of Douglas Vincent and Matthew
Murphy, who are co-inventors of the present invention. Our prior
patent discloses a pump actuated by a linear motor configured to
cause reciprocation of a flexible membrane, serving as a wall of a
fluid housing, that is in turn coupled to a pair of ball valves, in
a manner as to implement pulsatile fluid flow.
SUMMARY OF THE EMBODIMENTS
In accordance with one embodiment of the invention, a pulsatile
fluid pump system for driving a fluid pump assembly includes a
reciprocating linear motor having a magnet and a coil, the magnet
moving in relation to the coil, the coil having an electrical
input. The pulsatile fluid pump system further includes a
controller system having an electrical output coupled to the
electrical input of the coil, and the controller system is
configured to execute a waveform program defining an electrical
waveform at the electrical output. The waveform program is
configured to control operation of the linear motor by modification
of a feature, selected from the group consisting of amplitude,
frequency, shape, and combinations thereof, of the electrical
waveform at the electrical output. The waveform program is further
configured to accept a set of user-specifiable parameters defining
the performance of the linear motor and to modify the electrical
waveform in response to such parameters.
Alternatively or in addition, the pulsatile fluid pump system
further includes a graphic display, coupled to the controller
system, the controller system executing a graphics program
configured to cause the graphic display to show a set of
user-specifiable parameters defining the performance of the linear
motor.
Alternatively or in addition, the pulsatile fluid pump system
further includes a flow sensor mechanically coupled to a fluid path
including the integrated pump assembly, the flow sensor having an
electrical output coupled to the controller system, wherein the
controller system is executing a graphics program configured to
cause the graphic display to show a set of items, including values
of a set of user-specifiable parameters defining the performance of
the linear motor and values of a set of physical flow
characteristics.
Also alternatively or in addition, the set of items shown includes
an instantaneous flow rate waveform in near real-time.
Alternatively or in addition, the set of items shown includes an
instantaneous stroke volume waveform in near real-time.
Also alternatively or in addition, the waveform program is
configured to generate the electrical waveform at the electrical
output by repeatedly performing a multi-piece polynomial spline
algorithm in a manner responsive to a set of user-specifiable
parameters defining the performance of the linear motor.
In a related embodiment, the controller system has a storage system
in which is stored an archetype electrical waveform, and the
waveform program reads the archetype electrical waveform from the
storage system and modifies the archetype electrical waveform,
based upon a set of user-specifiable parameters defining the
performance of the linear motor, to generate the electrical
waveform at the electrical output.
Alternatively or in addition, the pulsatile fluid pump system
further includes a set of sensors, electrically coupled to the
controller system and configured to produce a set of sensor outputs
corresponding to pumping performance. The waveform program is
configured to generate the electrical waveform at the electrical
output in a manner responsive to the set of sensor outputs and a
set of user-specifiable parameters.
Also alternatively or in addition, the user of the pulsatile fluid
pump system may choose from a set of waveform programs.
Alternatively or in addition, the graphic display is touch
sensitive.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing features of embodiments will be more readily
understood by reference to the following detailed description,
taken with reference to the accompanying drawings, in which:
FIG. 1 is a vertical section of the pulsatile fluid pump system 301
showing the controller system 311, power amplifier 321, linear
motor 330 (coil 332, cooling fins 334, and magnet 339), push rod
assembly 341, flexible seal 351, control housing 361, and the
integral pump assembly 200.
FIG. 2 is an example of the touch-sensitive graphic display 400
user interface showing the user-specifiable motor parameters 401,
flow characteristics 411, and user-specifiable input parameters
421.
FIG. 3 is a vertical section of the push rod assembly 341.
FIG. 4 is a vertical section of the linear motor 330.
FIG. 5 is a block diagram describing a waveform program
FIG. 6 is a block diagram describing a first embodiment 511a of the
waveform program 511.
FIG. 7 is a block diagram describing a second embodiment 511b of
the waveform program 511.
FIG. 8 is a block diagram describing a graphics program 611.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
Definitions. As used in this description and the accompanying
claims, the following terms shall have the meanings indicated,
unless the context otherwise requires:
A "set" includes at least one member.
An "electrical waveform" is a waveform selected from the group
consisting of an electrical current waveform, a voltage waveform,
and combinations thereof.
The term "user-specifiable input parameter" includes a
user-definable attribute pertinent to an alarm setting or
calculation for a user interface, such as low flow limit 421a, high
flow limit 421b, and body surface area 421c (BSA), as well as
combinations of any of the foregoing attributes.
The term "user-specifiable parameter defining the performance of
the linear motor" in the course of pumping includes a motor
performance attribute such as stroke strength 401a, beat rate 401b,
flow rate, average flow rate, stroke volume, flow index, pulse
pressure, output pressure, magnet displacement, as well as
combinations of any of the foregoing attributes.
The term "physical flow characteristic" includes a measured
attribute such as stroke strength, beat rate, flow rate, average
flow rate 411a, stroke volume 411b, flow index 411c, pulse
pressure, flow rate waveform 412, stroke volume waveform 413,
duration over which the pump has been running (e.g., measured by
timer 414), as well as combinations of any of the foregoing
attributes. If an attribute is user-specified in a given embodiment
of the present invention, then measurement of the attribute is of
subsidiary importance since its value has been specified.
Similarly, if an attribute being measured has primary importance in
a given embodiment of the present invention, then the parameter
would not have been user-specified.
FIG. 1 is a vertical section of the pulsatile fluid pump system 301
showing the controller system 311 (with electrical output 311b),
power amplifier 321 (with electrical input 321a and electrical
output 321b), linear motor 330 (comprised of a stationary member
331 which includes a coil 332 [with electrical input 332a], a frame
333, and cooling fins 334, and a moving member which includes a
spring 338 of FIG. 4 and a magnet 339), position sensor 371, push
rod assembly 341 (comprised of a push rod 342 and force sensor
372), flexible seal 351, control housing 361, and chassis 363. An
integral pump assembly 200 (comprised of the pump-valving assembly
101 with chamber 102, diaphragm assembly 201, and peripheral flange
221a) is held by the peripheral flange 221a and compliant member
(not shown) in the channel 362 within the control housing 361. (In
these figures, like numbered items correspond to similar components
across different figures.)
FIG. 2 is an example of a touch-sensitive graphic display 400 user
interface showing user-specifiable motor parameters 401. In this
interface appear parameters stroke strength 401a and beat rate
401b. These parameters are a subset of user-specifiable parameters
defining the performance of the linear motor. Additionally, in this
interface appear flow characteristics 411 (average flow rate 411a,
stroke volume 411b, flow index 411c), flow rate waveform 412,
stroke volume waveform 413, and timer 414. These flow-based
attributes are a subset of physical flow characteristics.
Additionally, the user interface displays user-specifiable inputs
421 (low flow limit 421a, high flow limit 421b, and body surface
area 421c).
FIG. 3 is a vertical section of the push rod assembly 341 comprised
of a push rod 342 and force sensor 372.
FIG. 4 is a vertical section of the linear motor 330, showing the
coil 332 with electrical input 332a, the frame 333, the magnet
centering spring 338, and the magnet 339. Other components and
detail of the motor are provided in FIG. 1.
In FIG. 5, the waveform program 511 is a computer program executed
by the controller system 311 microprocessor 311c which accepts
input from a set of sensors 370 (including position sensor 371 of
FIG. 1, force sensor 372 of FIGS. 1 and 3, and an external flow
sensor 373 of FIG. 8), a set of user-specifiable motor parameters
401 (stroke strength 401a and beat rate 401b) defining performance
of a linear motor 330 in the course of pumping. Additionally, FIG.
5 shows a set of user-specifiable input parameters 421 (low flow
limit 421a, high flow limit 421b, and body surface area 421c). The
waveform program 511 outputs an electrical waveform 512, the result
of a set of algorithms 513, at the electrical output 311b. The
electrical output 311b is coupled to electrical input 332a of
linear motor 330.
There is growing consensus that desirable characteristics of a
pulsatile pump should include both sufficient hemodynamic energy
and a human-like waveform architecture. To evaluate pulsatile flow,
we choose the human heart as the best model: it delivers a proper
stroke volume at a natural cadence with a physiologic rest at the
end of each stroke, adapting to the physiologic demands of the
patient by adjusting the cardiac output, as the product of stroke
volume and beat rate. Via the left ventricle, the human heart
provides hemodynamic energy that results in a pressure wave that
propagates fully through the elastic arterial tree. It appears that
only a biomimetic stroke volume delivered in a biomimetic time
frame (like the native systolic contraction produced by the heart)
allows the elastic arterial tree to properly relax during the
diastolic phase. Use of continuous flow devices stretches the
elastic arterial wall but never allows proper relaxation, creating
constant and atypical stress on the endothelial cells and
interfering with natural baroreceptor sympathetic and
parasympathetic signaling, thus disrupting the body's homeostatic
control state.
The waveform program 511 causes the pulsatile fluid pump system 301
to replicate the ability of the left ventricle of the human heart
to deliver physiological hemodynamic energy proportional to a
user-specified stroke strength 401a by causing delivery of the
necessary fraction of the stroke volume of a pump chamber 102 in a
physiologic natural cadence at a user-specified beat rate 401b. It
is a user (a perfusionist) of the pulsatile fluid pump system 301
who adjusts the stroke strength 401a (an indirect specification of
stroke volume) and beat rate 401b to meet the physiologic demand of
the patient. Furthermore, the waveform program 511 replicates the
physiologic rest at the end of each stroke, thereby allowing
natural relaxation of the arterial tree.
The structure of a pulsatile pump in accordance with various
embodiments of the present invention can usefully reflect
attributes of the human heart. The human heart is preload
sensitive--the heart cannot "pull" blood into the left ventricle;
it can only allow the blood available to flow naturally into the
ventricle. The human heart is also afterload sensitive in that it
is responsive to the compliance and resistance in the downstream
vasculature and doesn't exert excess force on the blood, which
could damage the vasculature. Lastly, the left ventricle cannot
deliver blood that isn't in the ventricle when it contracts; there
is a limited bolus of blood that it can deliver.
The pulsatile fluid pump system 301 has similar attributes of
inherent safety: it is preload and afterload sensitive, and it is
limited in both the volume of blood it can deliver and the force at
which it can deliver that bolus of blood. When filling, the
pulsatile fluid pump system 301 allows gravity filling from the
venous reservoir, exerting minimal negative pressure. When
emptying, the linear motor 330 is inherently limited in the force
that it can generate by its design. As such, it cannot overpressure
the downstream tubing or vasculature, instead delivering less than
the volume of blood in the pump chamber 102, thereby only
delivering as much volume as the vasculature can receive.
The integral pump assembly 200 is analogous to a left ventricle of
the human heart; the inlet ball check valve assembly used in
various embodiments hereof is analogous to a mitral valve; and the
outlet ball check valve assembly used in various embodiments hereof
is analogous to an aortic valve. Like the human heart, the inlet
and outlet ball check valve assemblies are passive and require a
slight reversal of flow to close. This slight reversal of flow
mimics the slight reversal that occurs when the aortic valve of the
human heart closes.
In one embodiment of the present invention, shown in FIG. 6, the
waveform program 511a is a computer program executed by the
controller system 311 microprocessor 311c which accepts input from
a set of sensors 370, a set of user-specifiable motor parameters
401, and a set of user-specifiable input parameters 421. The
waveform program 511a is configured to simulate a waveform that has
been experimentally determined to be appropriate for embodiments of
the pulsatile fluid pump system 301 of the present invention. The
waveform program 511a simulates the experimentally determined
waveform by repeatedly performing a multi-piece polynomial spline
algorithm 513a and the resulting waveform is used to drive the
linear motor 330. In the event that the user changes one of the
user-specifiable motor parameters 401, the waveform program 511a
uses zero or more of the current and/or previous values from the
set of sensors 370, along with the set of user-specifiable motor
parameters 401, zero or more flow characteristics 411, zero or more
user-specifiable input parameters 421, and the current electrical
waveform 512a to create a new electrical waveform 512b. The
waveform program 511a outputs the new electrical waveform 512b,
consisting of discrete output voltages at defined time durations,
at the electrical output 311b. The electrical output 311b is
coupled to electrical input 332a of linear motor 330.
In another embodiment of the present invention, shown in FIG. 7,
the waveform program 511b is a computer program executed by the
controller system 311 microprocessor 311c which accepts input from
a set of sensors 370, a set of user-specifiable motor parameters
401, and a set of user-specifiable input parameters 421. The
waveform program 511b reads an archetype electrical waveform 512c
stored electronically within the controller system 311. The
waveform program 511b then uses an algorithm 513b to adjust the
archetype electrical waveform 512c. The algorithm 513b creates a
new electrical waveform 512b from the archetype electrical waveform
512c using zero or more of the current and/or previous values of
the set of sensors 370, along with the set of user-specifiable
motor parameters 401, zero or more flow characteristics 411, zero
or more user-specifiable input parameters 421, and the current
electrical waveform 512a. The waveform program 511b outputs the new
electrical waveform 512b, consisting of discrete output voltages at
defined time durations, at the electrical output 311b. The
electrical output 311b is coupled to electrical input 332a of
linear motor 330.
In FIG. 8, the graphics program 611 is a computer program executed
by the controller system 311, which accepts user-specifiable motor
parameters 401 and user-specifiable input parameters 421. The
graphics program 611 causes a set of current values of the
user-specifiable motor parameters 401, a set of flow
characteristics 411, and a set of user-specifiable input parameters
421 to be shown on the graphic display 400.
When the stroke strength 401a value transitions from zero to a
positive value, the graphics program 611 sets timer 414 to zero,
increments the timer 414 in real time, and causes, each second, the
updated timer 414 value to be shown on the graphic display 400.
When the stroke strength 401a value transitions from a positive
value to zero, the graphics program 611 stops incrementing the
timer 414 and causes the most recent value of timer 414 to be shown
on the graphic display 400.
The graphics program 611 accepts input from the flow sensor 373,
calculates the average flow rate 411a, and causes the average flow
rate 411a to be shown on the graphic display 400. The graphics
program 611 also causes, in near real-time, the instantaneous flow
rate as a flow rate waveform 412 to be shown on the graphic display
400.
The graphics program 611 also uses data from the flow sensor 373 to
calculate the average stroke volume 411b and cause the average
stroke volume 411b to be shown on the graphic display 400. The
graphics program 611 also causes, in near real-time, the total
volume of fluid currently delivered for a given stroke to be shown
on the graphic display 400. The total volume of fluid currently
delivered for a given stroke is the integral of instantaneous flow
as a stroke volume waveform 413 and is displayed as the shaded area
under the flow rate waveform 412.
The graphics program 611 accepts input of body surface area 421c
and calculates flow index 411c as the average flow rate 411a
divided by the body surface area 421c. The graphics program 611
further causes the body surface area 421c and calculated flow index
411c to be shown on the graphic display 400.
The graphics program 611 accepts input of low flow limit 421a and
high flow limit 421b, and causes the low flow limit 421a and high
flow limit 421b settings to be shown on the graphic display
400.
The embodiments of the invention described above are intended to be
merely exemplary; numerous variations and modifications will be
apparent to those skilled in the art. All such variations and
modifications are intended to be within the scope of the present
invention as defined in any appended claims.
* * * * *